DailyTech - China's Censorship Firewall Defeated

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IT China's Censorship Firewall Defeated
Tuan Nguyen (Blog) - July 4, 2006 3:14 PM

42 comment(s) - last by Creche.. on Jul 7 at 3:01 PM

Censorship continues to be a big concern for China

A group of computer experts from the University of Cambridge claims that they are now able to circumvent the censorship mechanism that China uses to block unwanted content from reaching its citizens. Certain words are banned and certain websites are also banned. A user sitting within the country's network will not be able to reach websites for which the government has deemed inappropriate. China itself has defended its right to police the Internet for its citizens many times.

The group of researchers say that China's firewall is based on a a series of Cisco routers and the products work by censoring keywords. When a user wishes to access a websites that's banned, the router returns reset packets to the foreign website, severing the connection -- the data transmission is stopped at the foreign end-point. Using this bit of information on how the Cisco routers work, the researchers were able to find their way around the firewall by creating a system that ignores the reset packets sent by the Chinese routers.

Along with their discovery, the researchers also found that it was possible to create a denial-of-service (DoS) attack from within the firewall using the router's own blocking mechanisms. By masquerading the source IP address of a banned website to one that's within China's network, the researchers are able to ban users from within the network from accessing a Chinese government website for example.

Richard Clayton, spokesperson for the laboratory at the university told reporters that the researchers had reported the findings to the Chinese Computer Emergency Response Team.

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VPN?

By Hare on 7/4/2006 4:26:22 PM , Rating: 2

What is actually preventing a user from making a VPN connection to a computer in lets say the UK or Sweden? No limitations since all traffic is tunneled (and encrypted) from legal computer in another country?

RE: VPN?

By Hypernova on 7/4/2006 4:54:46 PM , Rating: 2

Or ToR and other encrypted proxies for that matter. Thing is most people don't even know they exist or where to find them.

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RE: VPN?

By darkfoon on 7/4/2006 4:58:49 PM , Rating: 2

VPN requires a cooperating end-point, if you give a chinese person access to your VPN, the men in black suits may just show up at your door, and kindly ask you to stop breaking their laws.

Tor is a much better route, because its anonymous, and it doesnt bring anybody else into the problem except the participating party (e.g. chinese citizen)

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